Zirconium diboride powders synthesized by boro/carbothermal reaction using sol-gel technology

A single phase of zirconium diboride(ZrB2)powder was successfully synthesized by sol-gel method in Zr-B-C-O system, using zirconium oxychloride(ZrOCl2·8H2O), nano-scale boron and sucrose(C12H22O11)as the starting materials and propylene oxide(PO)as complexing agent at a low temperature. Simultaneously, the experimental and theoretical studies of ZrB2 synthesized by boro/carbothermal reduction from novel sol-gel technology were discussed. The results indicated that the pure rod-like ZrB2 powder without residual ZrO2 phase could be obtained with a B/Zr molar ratio of 3.5 at 1 400°C in argon atmosphere. Besides, in this study, a kinetic model for the Zr-B-C-O system producing ZrB2 by boro/carbothermal reaction was established based on thermodynamic analysis. It was also observed that, with the increase of reaction temperature, the reaction which produced ZrB2 powders changed from the borothermal reaction to boro/carbothermal reaction in the Zr-B-C-O system.